Random element order in XML document using XML::LibXML - perl

Question

I have a Perl script that reads a simple .csv file like below-
"header1","header2","header3","header4"
"12","12-JUL-2012","Active","Processed"
"13","11-JUL-2012","In Process","Pending"
"32","10-JUL-2012","Active","Processed"
"24","08-JUL-2012","Active","Processed"
.....
The aim is to convert this .csv to an .xml file something like below-
<ORDERS>
<LIST_G_ROWS>
<G_ROWS>
<header1>12</header1>
<header2>12-JUL-2012</header2>
<header3>Active</header3>
<header4>Processed</header4>
</G_ROWS>
<G_ROWS>
<header1>13</header1>
<header2>11-JUL-2012</header2>
<header3>In Process</header3>
<header4>Pending</header4>
</G_ROWS>
....
....
</LIST_G_ROWS>
</ORDERS>
I know that there is XML::CSV available in CPAN which will make my life easier but I want to make use of already installed XML::LibXML to create the XML, instead of installing XML::CSV. I was able to read the CSV and create the XML file as above without any issues, but I am getting a random order of the elements in the XML i.e. something like below. I need to have the order of the elements (child nodes) to be in sync with the .csv file as shown above, but I am not quite sure how do go around that. I am using a hash and sort() ing the hash didn't quite solve the problem either.
<ORDERS>
<LIST_G_ROWS>
<G_ROWS>
<header3>Active</header3>
<header1>12</header1>
<header4>Processed</header4>
<header2>12-JUL-2012</header2>
</G_ROWS>
......
and so on. Below is the snippet from my perl code
use XML::LibXML;
use strict;
my $outcsv="/path/to/data.csv";
my $$xmlFile="/path/to/data.xml";
my $headers = 0;
my $doc = XML::LibXML::Document->new('1.0', 'UTF-8');
my $root = $doc->createElement("ORDERS");
my $list = $doc->createElement("LIST_G_ROWS");
$root->appendChild($list);
open(IN,"$outcsv") || die "can not open $outcsv: $!\n";
while(<IN>){
chomp($_);
if ($headers == 0)
{
$_ =~ s/^\"//g; #remove starting (")
$_ =~ s/\"$//g; #remove trailing (")
#keys = split(/\",\"/,$_); #split per ","
s{^\s+|\s+$}{}g foreach #keys; #remove leading and trailing spaces from each field
$headers = 1;
}
else{
$_ =~ s/^\"//g; #remove starting (")
$_ =~ s/\"$//g; #remove trailing (")
#vals = split(/\",\"/,$_); #split per ","
s{^\s+|\s+$}{}g foreach #vals; #remove leading and trailing spaces from each field
my %tags = map {$keys[$_] => $vals[$_]} (0..#keys-1);
my $row = $doc->createElement("G_ROWS");
$list->appendChild($row);
for my $name (keys %tags) {
my $tag = $doc->createElement($name);
my $value = $tags{$name};
$tag->appendTextNode($value);
$row->appendChild($tag);
}
}
}
close(IN);
$doc->setDocumentElement($root);
open(OUT,">$xmlFile") || die "can not open $xmlFile: $!\n";
print OUT $doc->toString();
close(OUT);

Answer 1

You could forget the %tags hash entirely. Instead, loop over the indices of #keys:
for my $i (0 .. #keys - 1) {
my $key = $keys[$i];
my $value = $values[$i];
my $tag = $doc->createElement($key);
$tag->appendTextNode($value);
$row->appendChild($tag);
}
That way, the ordering of your keys is preserved. When a hash is used, the ordering is indeterminate.

Answer 2

Your program is far more involved than it needs to be. For convenience and reliability you should use Text::CSV to parse your CSV file.
The program below does what you need.
use strict;
use warnings;
use Text::CSV;
use XML::LibXML;
open my $csv_fh, '<', '/path/to/data.csv' or die $!;
my $csv = Text::CSV->new;
my $headers = $csv->getline($csv_fh);
my $doc = XML::LibXML::Document->new('1.0', 'UTF-8');
my $orders = $doc->createElement('ORDERS');
$doc->setDocumentElement($orders);
my $list = $orders->appendChild($doc->createElement('LIST_G_ROWS'));
while ( my $data = $csv->getline($csv_fh) ) {
my $rows = $list->appendChild($doc->createElement('G_ROWS'));
for my $i (0 .. $#$data) {
$rows->appendTextChild($headers->[$i], $data->[$i]);
}
}
print $doc->toFile('/path/to/data.xml', 1);
output
<?xml version="1.0" encoding="UTF-8"?>
<ORDERS>
<LIST_G_ROWS>
<G_ROWS>
<header1>12</header1>
<header2>12-JUL-2012</header2>
<header3>Active</header3>
<header4>Processed</header4>
</G_ROWS>
<G_ROWS>
<header1>13</header1>
<header2>11-JUL-2012</header2>
<header3>In Process</header3>
<header4>Pending</header4>
</G_ROWS>
<G_ROWS>
<header1>32</header1>
<header2>10-JUL-2012</header2>
<header3>Active</header3>
<header4>Processed</header4>
</G_ROWS>
<G_ROWS>
<header1>24</header1>
<header2>08-JUL-2012</header2>
<header3>Active</header3>
<header4>Processed</header4>
</G_ROWS>
</LIST_G_ROWS>
</ORDERS>
Update
Without the exotic options that Text::CSV provides, its functionality is fairly simple if its options are fixed. This alternative provides a subroutine csv_readline to replace the Text::CSV method readline. It works mostly in the same way as the module.
The output of this program is identical to that above.
use strict;
use warnings;
use XML::LibXML;
open my $csv_fh, '<', '/path/to/data.csv' or die $!;
my $doc = XML::LibXML::Document->new('1.0', 'UTF-8');
my $orders = $doc->createElement('ORDERS');
$doc->setDocumentElement($orders);
my $list = $orders->appendChild($doc->createElement('LIST_G_ROWS'));
my $headers = csv_getline($csv_fh);
while ( my $data = csv_getline($csv_fh) ) {
my $rows = $list->appendChild($doc->createElement('G_ROWS'));
for my $i (0 .. $#$data) {
$rows->appendTextChild($headers->[$i], $data->[$i]);
}
}
print $doc->toFile('/path/to/data.xml', 1);
sub csv_getline {
my $fh = shift;
defined (my $line = <$fh>) or return;
$line =~ s/\s*\z/,/;
[ map { /"(.*)"/ ? $1 : $_ } $line =~ /( " [^"]* " | [^,]* ) , /gx ];
}

Answer 3

Seems like something that XML::LibXml is an overkill for, just use XML::Simple and build the proper hash which will describe that XML structure, than dump it with XMLOut to an XML file